1. Field of the Invention
The present invention relates generally to a cooling system for an image forming machine and more particularly to a cooling system in which temperature inside an image forming machine is detected by a temperature sensor and the inside of the image forming machine is controlled not to exceed a predetermined temperature value by using a cooling fan.
2. Related Art
The conventional cooling system for an image forming machine shown in FIG. 1 is provided in a body 11 of the machine having an original sheet plate 12, a photo-sensitive drum 13, a printed substrate 14 on which a control circuit is provided, and a printed substrate 15 on which a drive circuit is provided for driving various motors, each mounting thereon a temperature sensor 22a, 22b, 22c and 22d, respectively. Each temperature sensors 22a, 22b, 22c and 22d is connected to a read-and-judgement circuit 16 as shown in FIG. 2, which reads each temperatures and judges if a cooling fan 18 is to be actuated through a drive control circuit 24 so that an excessive increase of the temperature inside the image forming machine is appropriately suppressed. The rotational speed of the fan 18 is selected from "HIGH", "MIDDLE" and "LOW" levels. Therefore, an operation and function of each mechanical parts of the image forming machine is not influenced by an excessive heat but stably and appropriately maintained.
However, the conventional cooling system thus constructed requires many temperature sensors be installed inside the image forming machine that would cause the machine be complicated in structure and increase the manufacturing cost. Thus the conventional cooling system is disadvantageous mechanically and economically. Further, since each of the temperature sensors 22a, 22b, 22c and 22d is controlled independently, it would be difficult to obtain an appropriate cooling operation due to an intricate control.